Glow plug

ABSTRACT

A glow plug has an elongated tubular housing and a convoluted tubular member located in and extending axially through this housing. A leading end portion of the tubular member is located proximal to the front end of the tubular housing. Fuel outlet means is provided in the front end portion and fuel inlet means are provided in the tubular member rearwardly of the outlet means. A glow pin extends through the center of the helix constituted by front tubular member and is electrically energizable for thereby indirectly heating fuel passing through the tubular member from the inlet means to the outlet means so that such fuel issues from the outlet means as flammable fuel vapor.

v References Cited UNITED STATES PATENTS 1,432,214 10/1922 Sperry...

1,931,379 10/1933 Graziano...,..................

Primary Examiner-Laurence M. Goodridge Attorney-Michael S. Striker ABSTRACT: A glow plug has an elongated tubular housing and a convoluted tubular member located in and extending axially through this housing. A leading end portion of the tubular member is located proximal to the front end of the tubular housing. Fuel outlet means is provided in the front end portion and fuel inlet means are provided in the tubular member rearwardly of the outlet means. A glow pin extends through the center of the helix constituted by front tubular member and is electrically energizable for thereby indirectly heating fuel passing through the tubular member from the inlet means 0 United States Patent Karl Wolf Stuttgart-Sonnenberg; Helmut Weyl, Bietigheim; Otto Beesch, Stuttgart-Sonnenberg, all of Germany 3,386 Jan. 16, 1970 [45] Patented Dec. 28, 1971 Robert Bosch GmbH Stuttgart, Germany [32] Priority Jan. 28, 1969 Germany P 19 03 999.7

9 Claims, 3 Drawing Figs.

[72] Inventors [21 Appl. No. [22] Filed [73] Assignee 154] GLOW PLUG to the outlet means so that such fuel issues from the outlet means as flammable fuel vapor.

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"4 A m m 0 m m l/ M W 2 m m1 S l mA PATENTED ntcaum SHEEIIUT 2 GLOW PLUG BACKGROUND OF THE INVENTION The present invention relates generally to glow plugs, and more particularly to glow plugs for use in diesel and related engines.

Such glow plugs are used as a starting aid in starting the diesel engines and multiple fuel engines. Conventionally they comprise a housing and a glow pin extending through the housing and being surrounded by a heating element convoluted about the glow pin. Fuel passes along the glow pin between the same and the housing and is heated before it issues from the housing, the purpose being that the fuel is to issue as flammable fuel vapor. However, it has been found that in these known constructions the dwell time of the fuel in the region of the glow pin is relatively short, with the result that the heat energy supplied to the glow pin is not fully utilized for vaporization of the fuel so that the latter is not fully vaporized. This has adverse influences on the efficiency of known glow plugs.

A further problem with these known constructions is the fact that they are capable of vaporizing only relatively small quantities of fuel per time unit and that they must be mounted in vertical or near vertical orientation to operate properly.

SUMMARY OF THE INVENTION It is, accordingly, a general object of the present invention to provide an improved glow plug for use in diesel and related engines.

More particularly, it is an object of the present invention to provide such an improved glow plug which is not possessed of the disadvantages described above with respect to the prior art.

A further object of the invention is to provide such a improved glow plug which permits the vaporization of greater quantities of fuel per time unit than is possible with known glow plugs.

A concomitant object of the invention is to provide an improved glow plug of the type under discussion which can be mounted in any desired orientation and is not limited to mounting in vertical or near vertical position.

In pursuance of the above objects, and others which will become apparent hereafter, the novel glow plug according to the present invention comprises according to one embodiment and briefly stated, an elongated tubular housing having a front end, and a convoluted tubular member located in and extending axially through this housing. The tubular member has a front end portion proximal to the front end of the housing.

Fuel outlet means is provided in the front end portion, and fuel inlet means in the tubular member rearwardly of the outlet means.

Heating means is provided for heating fuel passing through the tubular member from the inlet means to the outlet means and for thereby effecting issuance of such fuel from the outlet means as flammable fuel vapor.

It is particularly advantageous that the tubular member be helically convoluted about the glow pin which is electrically heated, so that by heat exchange of the tubular member with heated glow pin the fuel which advances through the convoluted tubular member is indirectly heated and vaporized. The vapor may be permitted to issue from the open end of the tubular member tangentially to the helix constituted by the latter, or it may issue through suitable apertures provided in the wall of the tubular member in the region of its open or outlet end.

Advantageously, the tubular member should be composed of scale resistant chrome nickel steel. More than one glow pin may be utilized. If a single glow pin is used as the heating element, the quantity of fuel vaporized in the construction according to the present invention is approximately l-l5 cm./min, If two glow pins are used which may be located sideby-side in axial parallelism with one another, then 20-30 cmP/min. fuel may be vaporized, with such a construction.

5 jects and advantages thereof, will be best understood from the following description of specific embodiments when read in connection with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWING FIG. I is a longitudinal section through a glow pin according to one embodiment of the invention;

FIG. 2 is an end view of the embodiment illustrated in FIG. 3, looking upwardly in the latter figure; and

FIG. 3 is an axial section through FIG. 2.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Discussing now firstly FIG. 1, and the embodiment illustrated therein, it is emphasized that reference numeral 10 identifies the suction manifold of an engine with which the novel glow plug is to be used, for instance a diesel engine. It is not necessary to illustrate further components of the engine because the engine as such does not form a part of the present invention and the suction manifold 10 has been shown only to provide an indication of the position and orientation of the glow pin with reference to the manifold.

A threaded nipple 11 is provided in the manifold 10 and into this nipple 11 there is threaded a glow plug according to the embodiment of FIG. 1, being protected against coming loose by the presence of a nut 12.

The glow plug in FIG. 1 comprises a housing including a lower portion 13 of relatively large internal diameter which accommodates axially therein a pin 14 of known construction. Convoluted about the glow pin 14 is a vaporizing element in form of a helically convoluted tubular member [5 advantageously consisting of chrome nickel steel. The tubular member 15 in nonconvoluted condition is approximately 40 cm. long and has an outer diameter of 3 mm. and an inner diameter of 2 mm. Of course, these dimensional details are given by way of example only. However, if they actually are present, then the axial length of the helix constituted by the convolutions of the tubular member 15 is approximately 40 mm.

A sleeve 16 is pushed onto the upper inlet end of the tubular member 15 and welded thereto. The sleeve 15 and a connecting nipple 17 through which fuel is to be admitted into the tubular member 15, are mounted in a connecting head 18 and secured therein in suitable manner, preferably by hard soldermg. v

The drawing shows that a trailing portion of the glow pin 14 also extends into the connecting head 18 and that its trailing end is sealed with reference to the connecting head l8 by a rubber sealing gasket 19 and two suitable sealing annuli 20 for instance of the type available under the trade name Resitex," so as to be sealed and insulated with reference to the connecting head 18. A nut 21 presses the annuli 20 and the sealing gasket 19 into a recess provided for this purpose in the connecting head 18. A dished spring 22 surrounds the free trailing end of the glow pin 14 and cooperates with a knurled nut 23 which is threaded onto this trailing end, so that by cooperation between the spring 22 and the nut 23 an electrical conductor may be releasably clamped between them and thus connected in electrically conductive relationship with the glow pin 14.

The connecting head l8together with the glow pin 14, nipple l7 and tubular member l5is inserted into the upper open end of the housing 13 and connected with it in suitable manner, preferably by hard soldering. Conversely a protective sleeve 24 is pressed into the open front end of the housing 13; it is provided with a plurality of air inlet apertures 24' through which air may enter from the suction manifold 10 of the englne.

The sleeve 24 defines with the leading end of the glow pin 14 a chamber which is concentric with the leading end and with the convoluted member a transverse divider extends normal to the axial extension of the sleeve 24, and a flame-holding sleeve 25 cooperates with the transverse divider 25 and subdivides the interior of the annular chamber defined between the leading end of the glow pin 14 and the circumferential wall of the sleeve 24, into a plurality of compartments.

In operation of the novel glow plug of the FIG. 1, diesel fuel or analogous fuel is admitted through the inlet nipple 17 from a source of supply and passes through the helically convoluted tubular member 15. ln so doing it is indirectly heated by heat exchange with the electrically heated glow pin 14 and becomes vaporized issuing as fuel vapor from the outlet apertures 15' which are provided in the front end portion of the tubular member 15 and which in the illustrated embodiment are oriented radially with reference to the leading portion of the glow pin 14. It will be seen that the apertures 15' communicate with a compartment 27 defined within the sleeve 24 by the presence of the transverse divider 25, and that the air inlet apertures 24' also communicate with this compartment 27. This compartment, therefore, receives the major portion of the issuing fuel vapor and of the incoming combustion supporting air. There exist, however, two gaps, through which the compartment 27 communicates respectively with the compartments28 and 29 both of which are located axially forwardly of thecompartment 27. One of these gaps is identified with reference numeral 25 and exists between the transverse divider 25 and the circumferential wall of the sleeve 24, so that it communicates with the compartment 28. The other gap is identified with reference numeral 25' and exists between the transverse divider 25which has an aperture-and the leading portion of the glow pin 14 which extends through this aperture. Thus, the gap 25 communicates with the compartment 29. This latter is defined by the flame holding sleeve 26 as shown.

The relatively small quantity of air/fuel vapor which enters into the compartment 29the latter being a compression chamber-is ignited at the free end portion or leading end portion of the glow pin 14 and the ignition flame in turn ignites the fuel-air mixture issuing downwardly or forwardly from the chamber 28, and by issuing from the chambers 28 and 29 serves additionally to ignite the fuel-air mixture which issues from the compartment 27 through the apertures 24 into the suction manifold 10.

By providing the elements 25 and 26 and subdividing the space between the circumferential wall of the sleeve 24 and the leading portion of the glow pin 14, we assure that there is always a flammable fuel-air mixture present in the actual combustion or ignition chamber 29 where the glow pin has its highest temperature. Thus, the mixture present in the chamber 29 will unfailingly be ignited and the ignition flame will reliably serve to ignite the remaining quanities of fuel-air mixture which issue from the novel glow plug into the suction manifold 10.

The glow plug in FIG. 1 is particularly advantageous if the fuel quantity which is to pass through the tubular member 15 does not exceed 10-15 cm./min. If the fuel quantity is in excess of this figure then it may be advantageous to utilize the embodiment illustrated in FIGS. 2 and 3 which comprises two glow plugs and a convoluted tubular member which is convoluted about them both. The two glow plugs identified in FlGS. 2 and 3 with reference numerals 30 and 31. The tubular member is identified with reference numeral 32 and corresponds to the tubular member 15 of FIG. 1. As in that Figure, the tubular member 32 is helically convoluted about the two glow pins 30 and 31 which extend in complete or at least substantial axial parallelism with one another. Apertures 32 are provided at the front end portion of the tubular member 32 and so oriented that fuel vapor issues through these apertures 32 radially in direction towards the leading end of the glow pin 30.

A connecting head 33 is provided in which the glow pins 30 and 31 are mounted, being electrically insulated and sealed by suitable means, for instance, a glass plug.

A fuel inlet nipple 31 is provided in the connecting head 33 and communicates with a steel sleeve 36 which in turn is hard soldered or otherwise connected with the open rear end of the tubular member 32, and is also secured by hard soldering or the like in the connecting head 33 together with the nipple 35.

The housing is identified with reference numeral 7 in the embodiments of FIGS. 2 and 3 and has press-fitted into its open rear end the connecting head 33 with the components secured to the latter. The connecting head 33 is hard soldered to the housing 37.

In FIG. 3 the suction manifold 38 of a diesel or analogous engine again has secured and extending into it the housing 37 in the same manner in which this has been described with reference to FIG. 1.

A protective sleeve 39 with air inlet apertures 39' is press fitted and/or otherwise secured in the open forward end of the housing 37. A flame holding sleeve 40 is located in the protective sleeve 39 and has projections 40 with which it is secured-by welding-to the sleeve 39. The interior of the flame holder sleeve 40 is subdivided by a divider wall 41 which extends axially of the sleeve 40 and is located between the leading portions of the two glow pins 30 and 31.

1n the longitudinal direction of the novel glow plug of FIGS. 2 and 3, the flame holder sleeve 40 and the divider wall 41 extend tojust below the fuel outlet apertures 32' in the tubular member 32 so that the fuel vapor issuing from the outlet openings 32' is directed only against the leading end of the glow pin 30 above the flame holding sleeve 40 and in the space surrounded by the protective sleeve 39. This results in the formation eddies which causes a flow of the air-fuel vapor mixture from above in downward direction in other words, towards the leading end of the glow plug. This mixture is further heated by the glow pin 30 and is ignited by the glow pin 31. The reason for this is that the latter becomes heated to a substantially higher temperature than the glow pin 30 because, unlike the latter, the glow pin 31 is not directly exposed to issuing fuel vapor emitted from the outlet openings 32' but instead has its leading end located in a separate combustion chamber delimited by the longitudinal separating wall 41. The fuel-air mixture passing through that chamber or compartment in which the leading portion of the glow pin 30 is located, becomes ignited by the heat of the leading portion of the glow pin 31 as it reaches the lower end of the chamber or compartment in which the leading portion of the glow pin 31 is located, that is the lower end of the longitudinal separating wall 41.

Under certain circumstances-for instance if a strong flow takes place in axial direction of the glow plug-it may be advantageous to place onto the lower end of the protective sleeve 39 a cup 42 cutouts 42 and with a slot 43 open at one side. The purpose is to reduce the flow of the fuel-air mixture and to facilitate its ignition.

It will be appreciated that with either embodiment illustrated, significantly greater quantities of fuel can be vaporized per time unit than is possible with the prior art constructions which do not utilize the convoluted tubular member 15 or 32, and that the novel glow plugs according to the present invention may be mounted in any desired manner and orientation without disadvantageous results on their operation.

It will be understood that each of the elements described above, or two or more together, may also find a useful application in other types of applications differing from the types described above.

While the invention has been illustrated and described as embodied in a glow plug for use in diesel and related engines it is not intended to be limited to the details shown, since various modifications and structural changes may be made without departing in any way from the spirit of the present invention.

Without further analysis, the foregoing will so fully reveal the gist of the present invention that others can, by applying current knowledge readily adapt it for various applications without omitting features that from the standpoint of prior art fairly constitute essential characteristics of the generic or specific aspects of this invention and, therefore, such adaptations should and are intended to be comprehended within the meaning and range of equivalence of the following claims.

What is claimed as new and desired to be protected by Letters Patent is set forth in the appended l. A glow plug for use in diesel and related engines, comprising an elongated tubular housing having a front end, a helically convoluted tubular member located in and extending axially through said housing, said tubular member having a front end portion proximal to said front end; fuel outlet means in said front end portion, and fuel inlet means in said tubular member rearwardly of said outlet means; and combined heating and igniting means for heating fuel passing through said tubular member from said inlet means to said outlet means so that such fuel issues from said outlet means as flammable fuel vapor, and having an igniting portion located in the region of said outlet means for contact with and igniting of said flammable fuel vapor.

2. A glow plug as defined in claim 1, wherein said combined heating and ignited means comprises at least one electrically energizable glow pin; and wherein said tubular member is helically convoluted about said glow pin in heat-exchanging relationship therewith.

3. A glow plug as defined in claim 1, said outlet means comprising a plurality of fuel vapor outlet openings provided in said front end portion of said tubular member.

4. A glow plug as defined in claim 2, wherein said front end portion projects outwardly of said front end of said housing; and further comprising a sleeve surrounding said front end portion with clearance and being secured to said housing; an aperture means in said sleeve; and wall means subdividing said sleeve and forming with said front end portion a plurality of communicating chambers arranged to facilitate admixture of air and fuel vapor.

5. A glow plug as defined in claim 4, said wall means comprising a dividing wall extending at least substantially normal to the longitudinal axis of said sleeve means and subdividing the latter into two axially adjacent chambers one of which is closer to said front end portion than the other, said air aperture means and said outlet means communicating with said one chamber, said igniting portion of said glow pin extending through said dividing wall into the other of said chambers; and gap means dimensioned to admit a relatively small quantity of fuel vapor and air from said one chamber into said other chamber for ignition therein.

6. A glow plug as defined in claim 1, wherein said heating means comprises at least two electrically energizable glow plugs extending axially through said housing; and wherein said tubular member is helically convoluted about both of said glow plugs in heat-exchanging relationship therewith.

7. A glow plug as defined in claim 6, said outlet means comprising a plurality of outlet openings facing towards at least one of said glow pins so that fuel vapor issues from said outlet openings in direction towards said one glow pin.

8. A glow plug as defined in claim 6; leading sections of said glow pins and of said tubular member projecting outwardly from said front end of said housing; further comprising a sleeve connected to said housing projecting forwardly from said front end and surrounding said leading sections with clearance.

9. A glow plug as defined in claim 8, further comprising dividing means in said sleeve and extending axially of the same intermediate said leading sections of said glow pins. 

1. A glow plug for use in diesel and related engines, comprising an elongated tubular housing having a front end, a helically convoluted tubular member located in and extending axially through said housing, said tubular member having a front end portion proximal to said front end; fuel outlet means in said front end portion, and fuel inlet means in said tubular member rearwardly of said outlet means; and combined heating and igniting means for heating fuel passing through said tubular member from said inlet means to said outlet means so that such fuel issues from said outlet means as flammable fuel vapor, and having an igniting portion located in the region of said outlet means for contact with and igniting of said flammable fuel vapor.
 2. A glow plug as defined in claim 1, wherein said combined heating and ignited means comprises at least one electrically energizable glow pin; and wherein said tubular member is helically convoluted about said glow pin in heat-exchanging relationship therewith.
 3. A glow plug as defined in claim 1, said outlet means comprising a plurality of fuel vapor outlet openings provided in said front end portion of said tubular member.
 4. A glow plug as defined in claim 2, wherein said front end portion projects outwardly of said front end of said housing; and further comprising a sleeve surrounding said front end portion with clearance and being secured to said housing; an aperture means in said sleeve; and wall means subdividing said sleeve and forming with said front end portion a plurality of communicating chambers arranged to facilitate admixture of air and fuel vapor.
 5. A glow plug as defined in claim 4, said wall means comprising a dividing wall extending at least substantially normal to the longitudinal axis of said sleeve means and subdividing the latter into two axially adjacent chambers one of which is closer to said front end portion than the other, said air aperture means and said outlet means commUnicating with said one chamber, said igniting portion of said glow pin extending through said dividing wall into the other of said chambers; and gap means dimensioned to admit a relatively small quantity of fuel vapor and air from said one chamber into said other chamber for ignition therein.
 6. A glow plug as defined in claim 1, wherein said heating means comprises at least two electrically energizable glow plugs extending axially through said housing; and wherein said tubular member is helically convoluted about both of said glow plugs in heat-exchanging relationship therewith.
 7. A glow plug as defined in claim 6, said outlet means comprising a plurality of outlet openings facing towards at least one of said glow pins so that fuel vapor issues from said outlet openings in direction towards said one glow pin.
 8. A glow plug as defined in claim 6; leading sections of said glow pins and of said tubular member projecting outwardly from said front end of said housing; further comprising a sleeve connected to said housing projecting forwardly from said front end and surrounding said leading sections with clearance.
 9. A glow plug as defined in claim 8, further comprising dividing means in said sleeve and extending axially of the same intermediate said leading sections of said glow pins. 